Seems like we could add a global setting for DOM to use wide mode, then, using a static property..

DataObjectManager::set_wide_mode(true);

overridden by the instance-level:

$myDOM->setWideMode(false);

But I don't see a reason to make changes to the JS, however, because then you're insulated from the DOM configuration, and I'd like to leave users with the highest level of control -- not stuck with what one user prefers.

The Archive contains 2 Files: DummyPage.php and ManyDummy.php. The DummyPage has a many_many relation to ManyDummy and uses ManyManyDataObjectManager to manage them.

Steps to reproduce the bug:
- copy DummyPage.php and MainDummy.php to mysite/code
- run /dev/build
- Login to the CMS and create a new DummyPage
- All tabs that come after the Tab that contains the DOM will be empty. Even the CMS Tabs like "Behavior", "ToDo" etc. will be empty. Unless you're using some browser that fixes invalid markup that is :)